Hotel

Description of Dr. Smith's 8 cage hotel

Citation: Smith, JC. Microstructure of the rat's intake of food, sucrose and saccharin in 24-hour tests. Neuroscience and Biobehavioral Reviews 24 (2000)199-212. PMID 10714383

Old stainless steel wire-bottom cages (dimensions: ?? X ?? X ?? cm) vs. Newer polycarbonate solid-bottom cages

Rats were housed in standard polycarbonate wire-top cages measuring 27 x 48 x 20 cm (more exactly 10.5" x 19" x 8") modified with holes cut in the front and in the rear of the cage to accommodate one feeding compartment and two drinking ports. A stainless steel nest box (?? x ?? x ?? cm) was placed inside the cage. At the front of the cage a stainless steel food compartment held a 4 oz glass food jar. When a rat entered the feeding compartment, its head broke an infrared beam located above the food jar so that every second during the 23-h period the rat had its head inside the compartment was recorded. Thus, time in the food compartment during a feeding episode, not amount of food intake, was measured. However, under baseline conditions, it has been shown that there is a high correlation between direct measures of food consumption (using load beams or videography) and the duration of a feeding bout [JODI and MEGAN PAPER].

A two-bottle stainless steel holder was located opposite the food compartment. In the present experiment, only one bottle was used; it was placed on the left side for the duration of the experiment. The sipper tube on the bottle was recessed behind a slot, allowing contact circuits to record each lick that the rat made during a 23-h period.

A computer recorded time spent in the food compartment and number of licks with 6-s resolution, meaning that after every 6-s bin, the number of seconds that the rat was in the food compartment and the number of licks on the sipper tube were recorded. This resulted in 13,800 6-s bins for every 23-h testing period during which the data were recorded. The computer was always started by 1000 h. A photo detector allowed the computer to record the time when the room lights went off and on during the 23-h period.

Variables collected by Dr. Smith's hotel

Any differences found in food and water intake during the experiment could be due to a change in a variety of factors: (1) the number of ingestive episodes (bouts), (2) the duration of these bouts, (3) the efficiency of feeding or drinking within the bouts, or (4) intake occurring outside of a bout (sampling). Feeding and drinking bouts were defined as follows:

For feeding, a bout started when a rat entered the food compartment for 3 sec. The bout had to include at least 30 s with the rat within the food compartment (i.e. breaking the infrared beam) in order to be included as a valid bout. The bout ended when the rat left and did not re-enter the food compartment again for 50 6-s bins (5 min).

For drinking, a bout started when a rat made 3 licks. A drinking bout had to contain at least 30 licks to be included as a valid bout. The bout ended when the rat did not lick for 50 6-s bins (5 min).

Using the daily food and fluid intake and the above bout criteria, the following dependent variables were measured or calculated for each day:

1. body weight, measured in grams
2. intake, measured in grams
3. number of daytime bouts
4. number of nighttime bouts
5. total number of bouts
6. total licks per bout
7. total number of licks included in all bouts
8. total number of licks NOT included in bouts (sampling licks)
9. total bout length, measured in number of 6-sec bins (multiple * 6 to get seconds)
10. volume per lick, measured in microliters
11. efficiency, in grams / minute (intake / ((total number of bouts)X(total bout duration))

Hotel File Formats

Raw File Format

6 byte header with 3 numbers. Each number is 16 bit integer, in lo-hi byte order

file_buffer [0],[1]  -- # of pts in the file -- maximum of 13800 (0x35E8)
file_buffer [2],[3] -- pt of lights OFF
file_buffer [4],[5] -- pt of lights ON

data pts represent 6-second bins. Each data pt is 1 byte. There are 3 channels of data pts.

For the food cup channel, the data pt contains number of seconds the infrared beam was broken per bin (range: 0-6)

For the 2 bottle channels, the data pt contains the number of beam breaks (licks) per bin (range: 0 - ~40)

The arrays of data pts for each data channel appear consecutively in the data file

file_buffer[6] to file_buffer[num_of_pts+5] = food cup data pts
file_buffer[6 + num_of_pts] to file_buffer[(2*num_of_pts)+5]  = left bottle data pts
file_buffer[6 + (2*num_of_pts)] to file_buffer[(3*num_of_pts)+5]  = right bottle data pts

CSV Files produced by LTAW

header line, followed by one line for each bout (note commas at end of line...)

name of bout file: "B<channel0-1>YYMMDD.CSV" <filename>,<nothing?>,<channel0-2>,<lightsoff_pt>,<totalcounts>,<lightson_pt>,<pts_per_bin?>,<startpt>,<endpt>,<validpt>,<minbin>,<IBIpts>, <zeroindexed bout num>,<startpt>,<endpt>,<counts>,

example:

CA15SET.C01,,0,7037,4181,11384,1,0,13797,3,50,30,
0,2222,2242,109,
1,3194,3269,392,
2,4201,4325,526,
3,4441,4686,977,
4,5628,5719,479,
5,6114,6251,678,
6,7139,7245,585,
7,7400,7492,459,
8,8204,8330,543,
9,9440,9685,1102,
10,10159,10275,607,
11,10782,10886,541

LTAW Variables

LIX	licks
BLIX	licks within bouts
BT	bout number
BTL	bout length (# of 6-sec bins)
LBT	Licks per bout
IBI	interbout interval

LTAW Bout Criteria

Minimum Size of a Valid Bin

units: counts per 6-second bin (licks/6seconds) or (number of seconds in food-cup)

if a bin has fewer than this number of licks or beam-break-seconds, then the data in this bin is ignored and not included in analysis

Example: if minimum size is set to 3, then the sequence of bins

0,0,1,0,0,2,0, 0,5,0,0,3,0,0,1,0,0,6

is filtered for purposes of analyses to become the sequence:

0,0,0,0,0,0,0, 0,5,0,0,3,0,0,0,0,0,6

Minimum number of invalid bins between bouts

Units: number of 6-second bins

The minimum interbout interval; typically is 5 minutes = 50 x 6-sec bins

Example:

 0,0,0,5,6,6,5,6,5,4,3,6,0,0,0,0, …[40 empty bins] ….0,6,5,6,5,4,5,0, …. [60 empty bins]….0,6,5,6,
       ^                                               ^          ^                         ^
       start 						                  same       end                       start
       of bout                                         bout       of bout                   of next bout

 

Minimum size of a valid bout:

Units: number of counts within the bout (licks or seconds in food-cup)

So if set to 30, then

a sequence of bins totalling 30 licks (or 30 seconds in the food cup) is a potential bout with on

Derived measures

Bout length in seconds = TOTBTL * 6

(sometimes "bout length" is referred to as "bout duration" or as "bout size" -- the use of size is ambiguous as to time or quantity e.g. of licks, so I prefer not to use size.

Bout Rate in licks/ second = (total licks per bout) / (total bout length in bins * 6)